I. Field
The present disclosure relates generally to electronics, and more specifically to a frequency synthesizer.
II. Background
A frequency synthesizer is a circuit that receives a reference signal at a reference frequency and generates an output signal at an output frequency. The output frequency may be related to the reference frequency by an integer ratio or a non-integer ratio, depending on the desired output frequency and the given reference frequency.
Frequency synthesizers are commonly used in various electronics devices. For example, a wireless device such as a cellular phone may include a frequency synthesizer to generate a local oscillator (LO) signal used for frequency downconversion or upconversion. The frequency synthesizer may receive a reference signal at a fixed frequency and generate the LO signal at a desired output frequency. The output frequency may be variable and dependent on the frequency channel used for communication. It is desirable to generate a clean LO signal having an accurate frequency in order to obtain good performance.